Voice and Data Cabling
Voice and Data Cabling by Alfred Hudson
Over the last two decades, voice and data communication systems have gone through significant changes. Data cabling systems have gradually changed from the simple connections used in the 1970s which featured shielded twisted–pair with coaxial cabling, to the more sophisticated and standardised cabling systems we have now. Voice and data cabling systems we use today consists of the UTP (Unshielded Twisted-Pair) and fiber-optic cabling. Considering the significant technological developments in the recent past, new ways of voice and data cabling such as the horizontal cabling, backbone cabling, and Intra-building cabling are commonly in use. For those of you who need to brush up on data cable check out the wiki page on data cables. It will help before you read this.
Horizontal Cabling
This type of cabling links a cross-connect system to a communication outlet in a working area. It is typically installed in a star configuration. In this type of cabling, a minimum of two category 5 cables (which are in four pairs each) are run to each working area. In addition, a four-pair UTP cable is run horizontally for each application. Here, each four-pair cable is terminated on an eight position modular connector and the communications outlet. On large floor areas of a building, an additional telecommunication closet is provided. This helps to limit the horizontal distribution to 90 meters or approximately 295 feet; a distance recommended in the standards. Supplementing the cross-connect hardware, communication closets are able to house equipment such as controllers, LAN hubs, bridges, multiplexers and routers in the cabinets or even on the racks. In the horizontal type of cabling, it is important to space the copper cross-connect system properly to accommodate the telecommunications outlets served by the closet. Wise designers also allow for an anticipated growth in their layout.
Backbone Cabling
This is a campus installation that runs from the main cross-connect to the other horizontal cross-connects. It is also connected to any intermediate cross-connects between buildings. Experienced cabling designers usually determine the kind of cables to use (either copper or fiber-optic) depending on the applications involved and the estimated distance.
This kind of installation is typically done with separate cables to serve each horizontal cross-connect and other intermediate cross-connects.
Intra-building Cabling
This one is used to provide a connection between the main cross-connects within a building and the horizontal cross-connect to the telecommunication terminal it serves. Here, if the Category 5 UTP multi-pair cable in the backbone is used, the number of copper wiring that serving each floor must be enough to accommodate all the horizontal cabling served by the backbone cable. In this case, the recommended minimum is two pairs for each circuit. In addition, a 25% spare should be allowed to accommodate future growth.
In the case of an inadequacy in the distance capabilities of copper, a multimode or single-mode fiber cabling is normally used in the backbone. In such a case, twelve fiber-optics are installed for every horizontal cross-connect. This provides for redundancy and ensures support for new services. Wherever there are floor penetrations, a backbone cabling is placed through the floor penetrations, shafts, conduits, and raceways. In such a case, professional cabling experts usually provide support for the cable in accordance with the manufacturers’ instructions and design. They also align the telecommunication closets vertically as much as possible. If it becomes difficult, they would be required to link the telecommunications closet and the backbone cabling. An inter-building backbone cabling provides a way of connecting the cross-connect with all the other intermediate cross-connects found in other buildings that it serves. Here, it is important that only cables rated for outdoor use such as the conduit, the buried or the aerial are used. For further safety, it is recommended that surge protection devices be used at both ends of all copper cable pairs in between buildings.
The main cross-connect or an intermediate cross-connect should be used as the common point of connection for all copper and fiber-optic backbone wiring, connection to telephone-company systems, inter-building cables, computers and private branch exchange. This allows for a central administration point for the voice communications network in the whole building as well as campus. It is advisable to use IDC connection hardware due to the huge number of cable terminations that are usually required in the main cross-connect unit.
Although the design of voice communication cabling systems has not had a radical change over the last two decades, significant changes in the technology of business applications need the integration of these applications with support for digital networks, integrated services, graphics and data. This presents the need to use sophisticated voice and data cabling systems such as the horizontal cabling, backbone cabling, and Intra-building cabling. The horizontal cabling system primarily links a cross-connect system to a communication outlet in a working area. On the other hand, the backbone cabling system runs from the main cross-connect to the other horizontal cross-connects. Finally, the intra-building cabling system is majorly used to provide a link between the main cross-connects within a building and the horizontal cross-connect, all the way to the telecommunication terminal it serves.
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